orbitdb/test/oplog/lamport-clock.test.js

import Clock from '../../src/oplog/lamport-clock.js'
import { strictEqual } from 'assert'

describe('Lamport Clock', () => {
  it('creates a new clock', () => {
    const id = 'A'
    const time = 0
    const clock = new Clock(id, time)
    strictEqual(clock.id, id)
    strictEqual(clock.time, time)
  })

  it('creates a new clock with default time', () => {
    const id = 'A'
    const time = 0
    const clock = new Clock(id)
    strictEqual(clock.id, id)
    strictEqual(clock.time, time)
  })

  it('creates a new clock with time starting at 1', () => {
    const id = 'A'
    const time = 1
    const clock = new Clock(id, time)
    strictEqual(clock.id, id)
    strictEqual(clock.time, time)
  })

  it('advances clock forward 1 tick', () => {
    const id = 'A'
    const time = 1
    const clock = new Clock(id)
    clock.tick()
    strictEqual(clock.time, time)
  })

  it('advances clock forward 2 ticks', () => {
    const id = 'A'
    const time = 2
    const clock = new Clock(id)
    clock.tick()
    clock.tick()
    strictEqual(clock.time, time)
  })

  it('merges clock2 into clock1', () => {
    const id1 = 'A'
    const clock1 = new Clock(id1)
    const id2 = 'B'
    const time2 = 2
    const clock2 = new Clock(id2, time2)

    clock1.merge(clock2)

    strictEqual(clock1.id, id1)
    strictEqual(clock1.time, time2)
  })

  it('merges two clocks with the same time', () => {
    const id1 = 'A'
    const time1 = 1
    const clock1 = new Clock(id1, time1)
    const id2 = 'B'
    const time2 = 1
    const clock2 = new Clock(id2, time2)

    clock1.merge(clock2)

    strictEqual(clock1.id, id1)
    strictEqual(clock1.time, time1)
  })

  it('clones a clock', () => {
    const id = 'A'
    const time = 1
    const clock = new Clock(id, time)
    const clonedClock = clock.clone()

    strictEqual(clonedClock.id, id)
    strictEqual(clonedClock.time, time)
  })

  describe('Compare clocks', () => {
    it('compares clocks when clock1\'s time is 1 less than clock2\'s', () => {
      const id1 = 'A'
      const time1 = 1
      const clock1 = new Clock(id1, time1)
      const id2 = 'B'
      const time2 = 2
      const clock2 = new Clock(id2, time2)

      const expected = -1

      strictEqual(Clock.compare(clock1, clock2), expected)
    })
    it('compares clocks when clock1\'s time is 3 less than clock2\'s', () => {
      const id1 = 'A'
      const time1 = 1
      const clock1 = new Clock(id1, time1)
      const id2 = 'B'
      const time2 = 4
      const clock2 = new Clock(id2, time2)

      const expected = -3

      strictEqual(Clock.compare(clock1, clock2), expected)
    })

    it('compares clocks when clock1\'s time is 1 more than clock2\'s', () => {
      const id1 = 'A'
      const time1 = 2
      const clock1 = new Clock(id1, time1)
      const id2 = 'B'
      const time2 = 1
      const clock2 = new Clock(id2, time2)

      const expected = 1

      strictEqual(Clock.compare(clock1, clock2), expected)
    })

    it('compares clocks when clock1\'s time is 3 more than clock2\'s', () => {
      const id1 = 'A'
      const time1 = 4
      const clock1 = new Clock(id1, time1)
      const id2 = 'B'
      const time2 = 1
      const clock2 = new Clock(id2, time2)

      const expected = 3

      strictEqual(Clock.compare(clock1, clock2), expected)
    })

    it('compares clocks when clock1\'s id is less than clock2\'s', () => {
      const id1 = 'A'
      const time1 = 1
      const clock1 = new Clock(id1, time1)
      const id2 = 'B'
      const time2 = 1
      const clock2 = new Clock(id2, time2)

      const expected = -1

      strictEqual(Clock.compare(clock1, clock2), expected)
    })

    it('compares clocks when clock1\'s id is more than clock2\'s', () => {
      const id1 = 'B'
      const time1 = 1
      const clock1 = new Clock(id1, time1)
      const id2 = 'A'
      const time2 = 1
      const clock2 = new Clock(id2, time2)

      const expected = 1

      strictEqual(Clock.compare(clock1, clock2), expected)
    })

    it('compares clocks when clock1 is the same as clock2', () => {
      const id = 'A'
      const time = 1
      const clock1 = new Clock(id, time)
      const clock2 = new Clock(id, time)

      const expected = 0

      strictEqual(Clock.compare(clock1, clock2), expected)
    })
  })
})